Elastomeric bicomponent fibers comprising block copolymers having high flow

ABSTRACT

Bicomponent fibers comprising a thermoplastic polymer and an elastomeric compound are made which can be continuously extruded from the melt at high production rates. The elastomeric compound has high flow and consists essentially of a selectively hydrogenated block copolymer and a tackifier resin, an alpha-olefin copolymer, an alpha-olefin terpolymer, a wax or mixtures thereof. In one embodiment the block copolymer has at least one polystyrene block of molecular weight from 5,000 to 7,000 and at least one polydiene block of molecular weight from 20,000 to 70,000 and having a vinyl content of greater than 60 mol %. In a second embodiment the block copolymer has a vinyl content of less than 60 mol %. The bicomponent fibers are useful for the manufacture of articles such as woven fabrics, spun bond non-woven fabrics or filters, staple fibers, yarns and bonded, carded webs.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. provisional patentapplication Ser. No. 60/549,570, filed Mar. 3, 2004, entitled BlockCopolymers having High Flow and High Elasticity and is acontinuation-in-part of U.S. patent application Ser. No. 11/069,268,filed Mar. 1, 2005 now U.S. Pat. No. 7,910,208, entitled ElastomericBicomponent Fibers Comprising Block Copolymers having High Flow.

FIELD OF THE INVENTION

The invention relates to bicomponent fibers comprising a thermoplasticpolymer and an elastomeric compound. In particular the elastomericcompound has high flow and comprises a block copolymer of mono alkenylarene and conjugated diene blocks and any one of a tackifying resin, analpha olefin copolymer, an alpha olefin terpolymer, a wax or mixturesthereof. The invention further relates to articles made from bicomponentfibers.

BACKGROUND

Fibers made from elastic materials find use in a variety of applicationsranging from woven fabrics to spunbond elastic mats to disposable,personal hygiene items. It would be of particular interest to usestyrenic block copolymers for such applications. However, the typicalphase-separated nature of block copolymer melts leads to high meltelasticity and high melt viscosity. In order to process styrenic blockcopolymers through small orifices, such as found in fiber spinnerets,expensive and specialized melt pump equipment would be required.Further, the high melt elasticities lead to fracture of the fiber as itexits the die, preventing the formation of continuous elastomericfibers. As a result, styrenic block copolymers have been found to beexceedingly difficult to process into continuous elastic fibers at highprocessing rates.

A further problem with styrenic block copolymers is their inherentstickiness in the melt. Because of this character, melt spun fibers ofstyrenic block copolymers tend to stick together, or self-adhere, duringprocessing. This effect is not desired and can be, in fact, tremendouslyproblematic when separate, continuous fibers are the goal. In additionto the result of an unacceptable fiber product, the self-adhesion of thefibers leads to equipment fouling and expensive shut-downs. Efforts toapply styrenic block copolymers in elastic fiber production have to datebeen met with significant challenges.

Himes taught the use of triblock/diblock copolymer blends as oneapproach to make elastomeric fibers in U.S. Pat. No. 4,892,903. Thesetypes of compositions have been found to have high viscosities and meltelasticities which have limited them to formation of discontinous andcontinuous fibers such as used in melt-blown, non-woven applications.

Bicomponent fibers comprising acid functionalized styrenic blockcopolymers have been taught by Greak in European Patent Application 0461 726. Conventional, selectively hydrogenated styrenic blockcopolymers which were acid functional were used to form side-by-sidebicomponent fibers with polyamides. While the acid functionalizationprovided increased adhesion between the two components, it is well knownin the art that acid functionalization leads to even higher meltviscosities and melt elasticities than in unfunctionalized blockcopolymers. Further, the side-by-side morphologies taught by Greak wouldnot prevent the inherently sticky fibers from self-adhering duringprocessing.

Bonded non-woven webs made using bicomponent fibers comprising, amongother polymers, conventional styrenic block copolymers and having avariety of morphologies has been taught by Austin in U.S. Pat. No.6,225,243. In particular, the sheath-core morphologies, with the corebeing comprised of styrenic block copolymers, provided fibers ofsuitably low stickiness to form non-woven webs.

However, high viscosity and melt elasticity of conventional styrenicblock copolymers continues to prevent high speed spinning of continuouselastomeric fibers. The present invention addresses these longstandingneeds by providing a high melt flow block copolymer which is able to beformed into continuous elastomeric bicomponent fibers.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a bicomponent fiber comprising athermoplastic polymer and an elastomeric compound wherein theelastomeric compound consists essentially of a selectively hydrogenatedblock copolymer having an S block and an E or E₁ block and having thegeneral formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)Xor mixtures thereof, wherein:

-   -   a. prior to hydrogenation the S block is a polystyrene block;    -   b. prior to hydrogenation the E block is a polydiene block,        selected from the group consisting of polybutadiene,        polyisoprene and mixtures thereof, having a molecular weight        from 40,000 to 70,000;    -   c. prior to hydrogenation the E₁ block is a polydiene block,        selected from the group consisting of polybutadiene,        polyisoprene, and mixtures thereof, having a molecular weight        from 20,000 to 35,000;    -   d. n has a value of 2 to 6 and X is the residue of a coupling        agent;    -   e. the styrene content of the block copolymer is from 13 to 25        weight percent;    -   f. the vinyl content of the polydiene block prior to        hydrogenation is from 70 to 85 mol percent;    -   g. the block copolymer includes less than 15 weight percent of        units having the general formula:        S-E or S-E₁        -   wherein S, E and E₁ are as already defined;    -   h. subsequent to hydrogenation about 0 to 10% of the styrene        double bonds have been hydrogenated and at least 80% of the        conjugated diene double bonds have been hydrogenated;    -   i. the molecular weight of each of the S blocks is from 5,000 to        7,000;        and a tackifying resin.

In another aspect, the present invention is a bicomponent fibercomprising a thermoplastic polymer and an elastomeric compound whereinthe elastomeric compound consists essentially of a selectivelyhydrogenated block copolymer having an S block and an E or E₁ block andhaving the general formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)Xor mixtures thereof, wherein:

-   -   a. prior to hydrogenation the S block is a polystyrene block;    -   b. prior to hydrogenation the E block is a polydiene block,        selected from the group consisting of polybutadiene,        polyisoprene and mixtures thereof, having a molecular weight        from 40,000 to 70,000;    -   c. prior to hydrogenation the E₁ block is a polydiene block,        selected from the group consisting of polybutadiene,        polyisoprene, and mixtures thereof, having a molecular weight        from 20,000 to 35,000;    -   d. n has a value of 2 to 6 and X is the residue of a coupling        agent;    -   e. the styrene content of the block copolymer is from 13 to 25        weight percent;    -   f. the vinyl content of the polydiene block prior to        hydrogenation is from 35 to 50 mol percent;    -   g. the block copolymer includes less than 15 weight percent of        units having the general formula:        S-E or S-E₁        -   wherein S, E and E₁ are as already defined;    -   h. subsequent to hydrogenation about 0 to 10% of the styrene        double bonds have been hydrogenated and at least 80% of the        conjugated diene double bonds have been hydrogenated;    -   i. the molecular weight of each of the S blocks is from 5,000 to        7,000        and any one of a tackifying resin, an alpha-olefin copolymer, an        alpha-olefin terpolymer, a wax or mixtures thereof.

In another aspect, the present invention is a bicomponent fibercomprising a thermoplastic polymer and an elastomeric compound whereinthe elastomeric compound consists essentially of a selectivelyhydrogenated block copolymer having an S block and an E or E₁ block andhaving the general formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)Xor mixtures thereof, wherein:

-   -   a. prior to hydrogenation the S block is a polystyrene block;    -   b. prior to hydrogenation the E block is a polydiene block,        selected from the group consisting of polybutadiene,        polyisoprene and mixtures thereof, having a molecular weight        from 40,000 to 70,000;    -   c. prior to hydrogenation the E₁ block is a polydiene block,        selected from the group consisting of polybutadiene,        polyisoprene, and mixtures thereof, having a molecular weight        from 20,000 to 35,000;    -   d. n has a value of 2 to 6 and X is the residue of a coupling        agent;    -   e. the styrene content of the block copolymer is from 13 to 25        weight percent;    -   f. the vinyl content of the polydiene block prior to        hydrogenation is from 70 to 85 mol percent;    -   g. the block copolymer includes less than 15 weight percent of        units having the general formula:        S-E or S-E₁        -   wherein S, E and E₁ are as already defined;    -   h. subsequent to hydrogenation about 0 to 10% of the styrene        double bonds have been hydrogenated and at least 80% of the        conjugated diene double bonds have been hydrogenated;    -   i. the molecular weight of each of the S blocks is from 5,000 to        7,000        and any one of an alpha-olefin copolymer, an alpha-olefin        terpolymer, a wax or mixtures thereof.

In another aspect the invention is an article such as an elastomericmono filament, a woven fabric, a spun bond non-woven fabric, a meltblown non-woven fabric or filter, a staple fiber, a yarn or a bonded,carded web comprising the bicomponent fiber described herein.

Importantly, the invention comprises an elastomeric compound having highmelt flow which allows processing of bicomponent fibers oncommercial-type equipment at high rates. The high melt flow of theelastomeric compound can be achieved with selectively hydrogenated blockcopolymers having high vinyl contents, sufficiently low molecularweights, presence of high flow components such as tackifying resins,alpha-olefin copolymers, alpha-olefin terpolymers or waxes, or by somecombination of these features.

FIGURES

FIG. 1 shows a cross-section of a bundle of bicomponent fibers of thepresent invention having a sheath-core morphology. The sheath iscomprised of a thermoplastic polymer and is apparent as an annularregion surrounding each core which is comprised of an elastomericcompound.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The bicomponent fibers of the present invention comprise a thermoplasticpolymer and an elastomeric compound comprising a selectivelyhydrogenated block copolymer, a tackifying resin, an alpha olefincopolymer, an alpha olefin terpolymer, a wax or mixtures thereof. Thebicomponent fiber is made by a coextrusion process in which thethermoplastic polymer and the elastomeric compound are metered to a dieor spinneret separately. Such a coextruded bicomponent fiber can have avariety of morphologies including, but not limited to, sheath-core,side-by-side, islands in the sea, bilobal, trilobal, and pie-section.

In the sheath-core embodiment of the present invention it is importantthat the sheath form the majority of the outside surface of the fiber.In particular, the sheath-core morphology wherein the sheath forms acovering about the core is one preferred embodiment. In this preferredmorphology, the core may be centered in the fiber cross-section or maybe off-center. The sheath may cover the core in a complete fashion overthe circumference of the fiber or may be only partially covering overthe circumference of the fiber. In the case where the covering ispartial about the circumference, the core makes up the majority of thevolume of the fiber. The volume ratio of the sheath to the core in thepresent invention is from 1/99 to 50/50. The preferred range of sheathto core volume ratio is 5/95 to 40/60 and the most preferred range is10/90 to 30/70. The sheath consists primarily of a thermoplastic polymerand the core consists of an elastomeric compound. As used herein“consists primarily” means greater than 80% on a volume basis.

In the islands-in-the-sea embodiment of the present invention it isimportant that the sea form a continuous matrix in which the islandsexist. The islands-in-the-sea morphology is another preferredembodiment. The islands are referred to as such because of theirappearance in cross-sectional views of the coextruded bicomponent fiber.The islands are actually microfibrous elements embedded in thecontinuous sea matrix. In this preferred embodiment the sea consistsprimarily of a thermoplastic polymer and the islands consist primarilyof an elastomeric compound. The volume ratio of the sea to the islandsin the present invention is from 1/99 to 50/50. The preferred range ofsea to island volume ratio is from 5/95 to 40/60 and the most preferredrange is from 10/90 to 30/70. It is well known in the art thatfree-standing microfibers can be produced from coextruded bicomponentfibers having islands-in-the-sea morphologies. Such microfibers areobtained by removing the sea matrix by a process such as selectivedissolution. In this way, the free-standing microfibers remain. Thebicomponent fibers of the present invention are suitable for producingelastomeric microfibers comprising the elastomeric compound.

In one embodiment the elastomeric compound comprises a selectivelyhydrogenated block copolymer having an S block and an E or E₁ block andhaving the general formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)Xor mixtures thereof, wherein: (a) prior to hydrogenation, the S block isa polystyrene block; (b) prior to hydrogenation, the E block or E₁ blockis a polydiene block, selected from the group consisting ofpolybutadiene, polyisoprene and mixtures thereof. The block copolymercan be linear or radial having three to six arms. General formulae forthe linear configurations include:S-E-S and/or (S-E₁)_(n) and/or (S-E₁)_(n)Swherein the E block is a polydiene block, selected from the groupconsisting of polybutadiene, polyisoprene and mixtures thereof, having amolecular weight of from 40,000 to 70,000; the E₁ block is a polydieneblock, selected from the group consisting of polybutadiene, polyisopreneand mixtures thereof, having a molecular weight of from 20,000 to35,000; and n has a value from 2 to 6, preferably from 2 to 4, an morepreferably an average of approximately 3. By example, the generalformula for the radial configurations having three and four armsinclude:

wherein the E₁ block is a polydiene block, selected from the groupconsisting of polybutadiene, polyisoprene and mixtures thereof, having amolecular weight of from 20,000 to 35,000; and X is a coupling agentresidue.

As used herein, the term “molecular weights” refers to the truemolecular weight in g/mol of the polymer or block of the copolymer. Themolecular weights referred to in this specification and claims can bemeasured with gel permeation chromatography (GPC) using polystyrenecalibration standards, such as is done according to ASTM 3536. GPC is awell-known method wherein polymers are separated according to molecularsize, the largest molecule eluting first. The chromatograph iscalibrated using commercially available polystyrene molecular weightstandards. The molecular weight of polymers measured using GPC socalibrated are styrene equivalent molecular weights. The styreneequivalent molecular weights may be converted to true molecular weightswhen the styrene content of the polymer and the vinyl content of thediene segments are known. The detector used is preferably a combinationultraviolet and refractive index detector. The molecular weightsexpressed herein are measured at the peak of the GPC trace, converted totrue molecular weights, and are commonly referred to as “peak molecularweights”.

The block copolymers of the present invention are prepared by anionicpolymerization of styrene and a diene selected from the group consistingof butadiene, isoprene and mixtures thereof. The polymerization isaccomplished by contacting the styrene and diene monomers with anorganoalkali metal compound in a suitable solvent at a temperaturewithin the range from about −150° C. to about 300° C., preferably at atemperature within the range from about 0° C. to about 100° C.Particularly effective anionic polymerization initiators areorganolithium compounds having the general formula RLi_(n) where R is analiphatic, cycloaliphatic, aromatic, or alkyl-substituted aromatichydrocarbon radical having from 1 to 20 carbon atoms; and n has a valueof 1 to 4. Preferred initiators include n-butyl lithium and sec-butyllithium. Methods for anionic polymerization are well known and can befound in such references as U.S. Pat. Nos. 4,039,593 and U.S. ReissuePat. No. Re 27,145.

The block copolymers of the present invention can be linear, linearcoupled, or a radial block copolymer having a mixture of 2 to 6 “arms”.Linear block copolymers can be made by polymerizing styrene to form afirst S block, adding butadiene to form an E block, and then addingadditional styrene to form a second S block. A linear coupled blockcopolymer is made by forming the first S block and E block and thencontacting the diblock with a difunctional coupling agent. A radialblock copolymer is prepared by using a coupling agent that is at leasttrifunctional.

Difunctional coupling agents useful for preparing linear blockcopolymers include, for example, methyl benzoate as disclosed in U.S.Pat. No. 3,766,301. Other coupling agents having two, three or fourfunctional groups useful for forming radial block copolymers include,for example, silicon tetrachloride, methyl-trichlorosilane,dimethyl-dichlorosilane and alkoxy silanes as disclosed in U.S. Pat.Nos. 3,244,664, 3,692,874, 4,076,915, 5,075,377, 5,272,214 and5,681,895; polyepoxides, polyisocyanates, polyimines, polyaldehydes,polyketones, polyanhydrides, polyesters, polyhalides as disclosed inU.S. Pat. No. 3,281,383; diesters as disclosed in U.S. Pat. No.3,594,452; methoxy silanes as disclosed in U.S. Pat. No. 3,880,954;divinyl benzene as disclosed in U.S. Pat. No. 3,985,830;1,3,5-benzenetricarboxylic acid trichloride as disclosed in U.S. Pat.No. 4,104,332; glycidoxytrimethoxy silanes as disclosed in U.S. Pat. No.4,185,042; and oxydipropylbis(trimethoxy silane) as disclosed in U.S.Pat. No. 4,379,891.

In one embodiment of the present invention, the coupling agent used canbe an alkoxy silane of the general formula R_(x)—Si—(OR′)_(y), where xis 0 or 1, x+y=3 or 4, R and R′ are the same or different, R is selectedfrom aryl, linear alkyl and branched alkyl hydrocarbon radicals, and R′is selected from linear and branched alkyl hydrocarbon radicals. Thearyl radicals preferably have from 6 to 12 carbon atoms. The alkylradicals preferably have I to 12 carbon atoms, more preferably from 1 to4 carbon atoms. Under melt conditions these alkoxy silane couplingagents can couple further to yield functionalities greater than 4.Preferred tetra alkoxy silanes are tetramethoxy silane (“TMSi”),tetraethoxy silane (“TESi”), tetrabutoxy silane (“TBSi”), andtetrakis(2-ethylhexyloxy)silane (“TEHSi”). Preferred trialkoxy silanesare methyl trimethoxy silane (“MTMS”), methyl triethoxy silane (“MTES”),isobutyl trimethoxy silane (“IBTMO”) and phenyl trimethoxy silane(“PhTMO”). Of these the more preferred are tetraethoxy silane and methyltrimethoxy silane.

In the embodiments of the present invention the polymer microstructurein the E and/or E₁ blocks is modified to control the vinyl content ofthe polymerized diene. This vinyl configuration can be achieved by theuse of a control agent during polymerization of the diene. A typicalagent is diethyl ether. See U.S. Pat. No. Re 27,145 and U.S. Pat. No.5,777,031, the disclosure of which is hereby incorporated by reference.Any microstructure control agent known to those of ordinary skill in theart of preparing block copolymers to be useful can be used to preparethe block copolymers of the present invention.

In one embodiment the vinyl content is high. The block copolymers areprepared so that they have from about 60 to about 85 mol percent vinylin the E and/or E₁ blocks prior to hydrogenation. In another embodiment,the block copolymers are prepared so that they have from about 65 toabout 85 mol percent vinyl content. In still another embodiment, theblock copolymers are prepared so that they have from about 70 to about85 mol percent vinyl content. Another embodiment of the presentinvention includes block copolymers prepared so that they have fromabout 73 to about 83 mol percent vinyl content in the E and/or E₁blocks.

In another embodiment the block copolymer of the present invention has avinyl content from about 25 to about 59 mol percent in the E and/or E₁blocks prior to hydrogenation. In this embodiment the preferred vinylcontent is from about 35 to about 50 mol percent and in the mostpreferred embodiment the vinyl content is from 37 to 47 mol percent inthe E and/or E₁ blocks.

In one embodiment, the present invention is a hydrogenated blockcopolymer. The hydrogenated block copolymers of the present inventionare selectively hydrogenated using any of the several hydrogenationprocesses know in the art. For example the hydrogenation may beaccomplished using methods such as those taught, for example, in U.S.Pat. Nos. 3,494,942; 3,634,594; 3,670,054; 3,700,633; and Re. 27,145,the disclosures of which are hereby incorporated by reference. Anyhydrogenation method that is selective for the double bonds in theconjugated polydiene blocks, leaving the aromatic unsaturation in thepolystyrene blocks substantially intact, can be used to prepare thehydrogenated block copolymers of the present invention.

The methods known in the prior art and useful for preparing thehydrogenated block copolymers of the present invention involve the useof a suitable catalyst, particularly a catalyst or catalyst precursorcomprising an iron group metal atom, particularly nickel or cobalt, anda suitable reducing agent such as an aluminum alkyl. Also useful aretitanium based catalyst systems. In general, the hydrogenation can beaccomplished in a suitable solvent at a temperature within the rangefrom about 20° C. to about 100° C., and at a hydrogen partial pressurewithin the range from about 100 psig (689 kPa) to about 5,000 psig(34,473 kPa). Catalyst concentrations within the range from about 10 ppmto about 500 ppm by wt of iron group metal based on total solution aregenerally used and contacting at hydrogenation conditions is generallycontinued for a period of time with the range from about 60 to about 240minutes. After the hydrogenation is completed, the hydrogenationcatalyst and catalyst residue will, generally, be separated from thepolymer.

In the practice of the present invention, the hydrogenated blockcopolymers have a hydrogenation degree greater than 80 percent. Thismeans that more than from 80 percent of the conjugated diene doublebonds in the E or E₁ block has been hydrogenated from an alkene to analkane. In one embodiment, the E or E₁ block has a hydrogenation degreegreater than about 90 percent. In another embodiment, the E or E₁ blockhas a hydrogenation degree greater than about 95 percent.

In the practice of the present invention, the styrene content of theblock copolymer is from about 13 percent to about 25 weight percent. Inone embodiment, the styrene content of the block copolymer is from about15 percent to about 24 percent. Any styrene content within these rangescan be used with the present invention. Subsequent to hydrogenation,from 0 to 10 percent of the styrene double bonds in the S blocks havebeen hydrogenated in the practice of the present invention.

The molecular weight of each of the S blocks in the block copolymers ofthe present invention is from about 5,000 to about 7,000 in the blockcopolymers of the present invention. In one embodiment, the molecularweight of each of the S blocks is from about 5,800 to about 6,600. The Sblocks of the block copolymers of the present invention can be apolystyrene block having any molecular weight within these ranges.

In the practice of the present invention, the E blocks are a singlepolydiene block. These polydiene blocks can have molecular weights thatrange from about 40,000 to about 70,000. The E₁ block is a polydieneblock having a molecular weight range of from about 20,000 to about35,000. In one embodiment, the molecular weight range of the E block isfrom about 45,000 to about 60,000, and the molecular weight range foreach E₁ block of a coupled block copolymer, prior to being coupled, isfrom about 22,500 to about 30,000.

One advantage of the present invention over conventional elastomericcompounds comprising hydrogenated block copolymer is that the inventiveelastomeric compounds have high melt flows that allow them to be easilymolded or continuously extruded into shapes or films or spun intofibers. This property allows end users to avoid or at least limit theuse of additives that degrade properties, cause area contamination,smoking, and even build up on molds and dies.

For the purposes of the present invention, the term “melt index” is ameasure of the melt flow of the polymer according ASTM D1238 at 230° C.and 2.16 kg weight. It is expressed in units of grams of polymer passingthrough a melt rheometer orifice in 10 minutes. The hydrogenated blockcopolymers of the present invention have a desirable high melt indexallowing for easy processing. In one embodiment, the hydrogenated blockcopolymers of the present invention have a melt index of greater than orequal to 9. In another embodiment, the hydrogenated block copolymers ofthe present invention have a melt index of at least 15. In still anotherembodiment, the hydrogenated block copolymers of the present inventionhave a melt index of at least 40. Another embodiment of the presentinvention includes hydrogenated block copolymers having a melt index offrom about 20 to about 100. Still another embodiment of the presentinvention includes hydrogenated block copolymers having a melt index offrom about 50 to about 85.

The hydrogenated block copolymers of the present invention also are verylow in contaminants that can cause these undesirable effects, such asdiblocks from inefficient coupling. The block copolymers andhydrogenated block copolymers of the present invention have less than 15weight percent of diblock content, such diblocks having the generalformula:SE or SE₁wherein S, E and E₁ are as previously defined. In one embodiment, thediblock level is less than 10 percent in another embodiment less than 8percent. For example, where the structure of the hydrogenated blockcopolymer is (S-E₁)₂X, the block copolymer contains less than 10% of theS-E₁ species. All percentages are by weight.

One characteristic of the hydrogenated block copolymers of the presentinvention is that they have a low order-disorder temperature. Theorder-disorder temperature (ODT) of the hydrogenated block copolymers ofthe present invention is typically less than about 300° C. Above 300° C.the polymer is more difficult to process and can be subject todegradation during processing. ODT's of the block copolymer of 250° C.or less are preferred and ODT's of 225° C. or less are most preferred.For purposes of the present invention, the order-disorder temperature isdefined as the temperature above which a zero shear viscosity can bemeasured by capillary rheology or dynamic rheology. Importantly,combinations of the hydrogenated block copolymers of the presentinvention with tackifiers, alpha-olefin copolymers, alpha-olefinterpolymers, waxes and the like can lead to blends having suitably lowODTs.

Exemplary thermoplastic polymers include polyolefin homo-, co- orterpolymers made by conventional Ziegler-Natta or single sitemetallocene catalysts. Example of such polyolefins are ethylenehomopolymers, ethylene/alpha-olefin copolymers, propylene homopolymers,propylene/alpha-olefin copolymers, impact polypropylene copolymers,ethylene/propylene/alpha-olefin terpolymers, butylene homopolymers,butylene/alpha olefin copolymers, and other alpha olefin copolymers orinterpolymers. In the present invention the alpha-olefin is 1-butene,1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene,1-decene, 1-dodecene and the like.

Representative polyethylenes include, for example, but are not limitedto, substantially linear ethylene polymers, homogeneously branchedlinear ethylene polymers, heterogeneously branched linear ethylenepolymers, including linear low density polyethylene (LLDPE), ultra orvery low density polyethylene (ULDPE or VLDPE), medium densitypolyethylene (MDPE), high density polyethylene (HDPE) and high pressurelow density polyethylene (LDPE).

When the thermoplastic polymer is polyethylene, the melt flow rate, alsoreferred to as melt flow index, must be at least 25 g/10 min at 190° C.and 2.16 kg weight according to ASTM D1238. The preferred type ofpolyethylene is linear low density polyethylene.

Representative polypropylenes include, for example, but are not limitedto, substantially isotactic propylene homopolymers, random alphaolefin/propylene copolymers where propylene is the major component on amolar basis and polypropylene impact copolymers where the polymer matrixis primarily a polypropylene homopolymer or random copolymer and therubber phase is an alpha-olefin/propylene random copolymer. Suitablemelt flow rates of polypropylenes are at least 10 g/10 min at 230° C.and 2.16 kg according to ASTM D1238. More preferred are melt flow ratesof at least 20 g/10 min. Polypropylene homopolymers are the preferredtype of polypropylene.

Terpolymers comprising styrene are also suitable and includeethylene/styrene/alpha olefins and propylene/styrene/alpha olefins.Suitable melt flow rates of styrene containing terpolymers are at least10 g/10 min at 230° C. and 2.16 kg according to ASTM D1238.

Examples of ethylene/alpha-olefin copolymers, propylene/alpha-olefincopolymers and ethylene/propylene/alpha-olefin terpolymers include, butare not limited to, AFFINITY, ENGAGE and VERSIFY polymers from DowChemical and EXACT and VISTAMAXX polymers from Exxon Mobil. Suitablemelt flow rates of such copolymers must be at least 10 g/10 min at 230°C. and 2.16 kg weight according to ASTM D1238. In the present inventioninclusion of ethylene/alpha-olefin and propylene/alpha-olefin copolymersand ethylene/propylene/alpha-olefin terpolymers in the elastomericcompound serves to improve spinning performance, increase the tensilestrength, and decrease the stickiness of the fibers. The amount of co-or terpolymer in the elastomer compound is from 5 to 90 wt %. When theelastomeric compound is made of a minority of co- or terpolymer theelastic properties, including tensile set and recovered energy, of thebicomponent fiber are optimal. The preferred amount of co- or terpolymeris from 5 to 49 wt % and the most preferred amount is from 5 to 20 wt %.

Still other thermoplastic polymers included herein are polyvinylchloride (PVC) and blends of PVC with other materials, polyamides andpolyesters such as poly(ethylene terephthalate), poly(butyleneterephthalate) and poly(trimethylene terephthalate). Regardless of thespecific type, the thermoplastic polymer must have a melt flow ratesuitable for processing into fibers or components of fibers.

In the embodiments of the present invention it is especially useful toinclude resins compatible with the rubber E and/or E₁ blocks of theelastomeric compound. This serves to promote the flow of the elastomericcompound. Various resins are known, and are discussed, e.g., in U.S.Pat. Nos. 4,789,699; 4,294,936; and 3,783,072, the contents of which,with respect to the resins, are incorporated herein by reference. Anyresin can be used which is compatible with the rubber E and/or E₁ blocksof the elastomeric compound and/or the polyolefin, and can withstand thehigh processing (e.g., extrusion) temperatures. Generally, hydrogenatedhydrocarbon resins are preferred resins, because of their bettertemperature stability. Examples illustrative of useful resins arehydrogenated hydrocarbon resins such as low molecular weight, fullyhydrogenated REGALREZ® (Eastman Chemical), ARKONO® (Arakawa Chemical)series resins, and terpene hydrocarbons such as ZONATAC®501 Lite(Arizona Chemical). The present invention is not limited to use of theresins listed here. In general, the resin may be selected from the groupconsisting of C₅ hydrocarbon resins, hydrogenated C₅ hydrocarbon resins,styrenated C₅ resins, C₅/C₉ resins, styrenated terpene resins, fullyhydrogenated or partially hydrogenated C₉ hydrocarbon resins, rosinsesters, rosins derivatives and mixtures thereof. One of ordinary skillin the art will understand that other resins which are compatible withthe components of the composition and can withstand the high processingtemperatures, and can achieve the objectives of the present invention,can also be used. The tackifier makes up the minor amount in theelastomer compound. The amount of tackifier is from 1 to 49 wt % basisthe elastomer compound mass. When the amount of tackifier is less than 1wt % the effect on elastomer compound flow is negligible. When theamount of tackifier is 50 wt % or greater the elastomeric properties ofthe bicomponent fiber are compromised. The preferred amount of tackifieris from 5 to 30 wt % and the most preferred is from 5 to 15 wt %.

The bicomponent fiber may also comprise a wax to promote flow and/orcompatibility. Suitable waxes are those having a congealing point offrom 50 to 70° C. Suitable amounts of wax are from 0.1 to 75% w,preferably from 5 to 60% wt based on the weight of the elastomericcompound. Animal, insect, vegetable, synthetic and mineral waxes may beused with those derived from mineral oils being preferred. Examples ofmineral oil waxes include bright stock slack wax, medium machine oilslack wax, high melting point waxes and microcrystalline waxes. In thecase of slack waxes up to 25% w of oil may be present. Additives toincrease the congealing point of the wax may also be present.

When the elastomeric compound is composed of a hydrogenated blockcopolymer and other components such as tackifier resins, alpha-olefincopolymers, alpha-olefin terpolymers or other processing aids andadditives, the elastomeric compound has a desirable high melt indexallowing for easy processing In one embodiment, the elastomericcompounds of the present invention have a melt index of greater than orequal to 12. In another embodiment, the elastomeric compounds of thepresent invention have a melt index of at least 15. In still anotherembodiment, the elastomeric compounds of the present invention have amelt index of at least 40. Another embodiment of the present inventionincludes elastomeric compounds having a melt index of from about 20 toabout 100. Still another embodiment of the present invention includeselastomeric compounds having a melt index of from about 50 to about 85.

The bicomponent fiber may also comprise a polymer extending oil. The oilmay be incorporated to improve the processability of the fiber or toenhance its softness. Especially preferred are the types of oil that arecompatible with the E and/or E₁ of the block copolymer. While oils ofhigher aromatics content are satisfactory, those petroleum-based whiteoils having low volatility and less than 50% aromatic content arepreferred. The oils should additionally have low volatility, preferablehaving an initial boiling point above about 260° C. The amount of oilemployed varies from about 0 to about 300 parts by weight per hundredparts by weight rubber, or block copolymer, preferably about 20 to about150 parts by weight.

The elastomeric compound is typically stabilized by the addition of anantioxidant or mixture of antioxidants. Frequently, a stericallyhindered phenolic stabilizer is used, or a phosphorus-based stabilizeris used in combination with a sterically hindered phenolic stabilizer,such as disclosed in Japanese patent No. 94055772; or a combination ofphenolic stabilizers is used, such as disclosed in Japanese patent No.94078376.

It is sometimes desirable to use processing aids and other additives inthe elastomeric compound. Exemplary of such aids and additives aremembers selected from the group consisting of other block copolymers,olefin polymers, styrene polymers, fillers, reinforcements, lubricants,pigments, dyes, optical brighteners, bluing agents and flame retardantsand mixtures thereof.

The bicomponent fibers of the present invention can be used to form avariety of articles. These articles include elastic mono filaments,woven fabrics, spun bond non-woven fabrics or filters, melt-blownfabrics, staple fibers, yarns, bonded, carded webs, and the like. Any ofthe processes typically used to make these articles can be employed whenthey are equipped to extrude two materials into a bicomponent fiber.

In particular, non-woven fabrics or webs can be formed by any of theprocesses known in the art. One process, typically referred to asspunbond, is well known in the art. U.S. Pat. No. 4,405,297 describes atypical spunbond processes. The spunbond process commonly comprisesextruding the fibers from the melt through a spinneret, quenching and/ordrawing the fibers using an air flow, and collecting and bonding thenon-woven web. The bonding of the non-woven web is typicallyaccomplished by any thermal, chemical or mechanical methods, includingwater entanglement and needle punch processes, effective in creating amultiplicity of intermediate bonds among the fibers of the web. Thenon-woven webs of the present invention can also be formed usingmelt-blown process such as described in U.S. Pat. No. 5,290,626. Cardedwebs may be formed from non-woven webs by folding and bonding thenon-woven web upon itself in the cross machine direction.

The non-woven fabrics of the present invention can be used for a varietyof elastic fabrics such as diapers, waistbands, stretch panels,disposable garments, medical and personal hygiene articles, filters, andthe like.

Elastic mono-filaments of the present invention are continuous, single,bicomponent fibers used for a variety of purposes and can be formed byany of the known methods of the art comprising spinning, drawing,quenching and winding. As used herein, staple fiber means cut or choppedsegments of the continuously coextruded bicomponent fiber.

Yarns of the bicomponent fibers can be formed by common processes. U.S.Pat. No. 6,113,825 teaches the general process of yarn formation. Ingeneral, the process comprises melt extrusion of multiple fibers from aspinneret, drawing and winding the filaments together to form amulti-filament yarn, extending or stretching the yarn optionally throughone or more thermal treatment zones, and cooling and winding the yarn.

The articles of the present invention can be used alone or incombination with other articles made with the bicomponent fibers or withother classes of materials. As an example, non-woven webs can becombined with elastic mono-filaments to provide elastic stretch panels.As another example, non-woven webs can be bonded to othernon-elastomeric non-woven webs or polymeric films of many types.

In the process of producing the bicomponent fiber of the presentinvention two separate single screw extruders are used to extrude thesheath polymer and core polymer into two separate melt pumps. Followingthe melt pumps, the polymers are brought together into their bicomponentconfiguration in the spinneret via a series of plates and baffles. Uponexiting the spinneret the fibers are cooled/quenched via a cold airquench cabinet. After quenching the fibers are drawn via an aspirator ora series of cold rolls. In the case that cold rolls are used, the fibersare taken up onto a winder. In the case that an aspirator is used, thefibers are allowed to collect in a drum beneath the aspirator.

One important aspect of the process is the rate at which the bicomponentfibers may be produced. The high flow characteristics presented by theinventive fibers allows high extrusion rates. This is important from apractical sense since commercial equipment operates at high extrusionrates. In this way, economic throughputs can be achieved. With thebicomponent fiber compositions of the present invention spinning speedsof greater than 800 meters per minute (mpm) are achieved. The morepreferred spees are about 1000 mpm or greater and the most preferredspeeds are about 1500 mpm or greater.

For the applications disclosed herein, fine diameter fibers arepreferred. These fine diameter fibers are extremely efficient elasticmaterials in the sense that very small amounts of material can be usedto affect elastic behavior in articles so composed. The fine diameterfibers may be a single bicomponent fiber or may be composed of multiplebicomponent filaments. In the present invention bicomponent fibershaving a denier (grams per 9000 m fiber or filament) from 0.1 to 30 canbe made. More preferred are fibers having a denier from 0.5 to 20 andmost preferred are fibers having a denier from 1 to 10.

EXAMPLES

The term “elastic” is used herein to mean any material which, uponapplication of a biasing force, is stretchable, that is, elongatable atleast about 60 percent (i.e., to a stretched, biased length which is atleast about 160 percent of its relaxed unbiased length) and which, willrecover at least 40 percent of its elongation upon release of thestretching, elongating force. A hypothetical example would be a one (1)inch sample of a material which is elongatable to at least 1.60 inches(4.06 cm) and which, upon being elongated to 1.60 inches (4.06 cm) andreleased, will recover to a length of not more than 1.27 inches (3.23cm). Many elastic materials may be elongated by much more than 60percent (i.e., much more than 160 percent of their relaxed length), forexample, elongated 100 percent or more, and many of these will recoverto substantially their initial relaxed length, for example, to within105 percent of their initial relaxed length, upon release of thestretching force.

The elasticity was measured on yarns formed from the bicomponent fibersas the percent strain recovery at 100 percent elongation. The yarnconsisted of a multiplicity of individual continuous bicomponentfilaments ranging in number from 36 to 144 depending upon the number ofholes in the spinneret. The yarn was stretched manually to 100%elongation and then allowed to relax. The relaxed length of the yarn wasthen measured and the percent recovery calculated. In this method theelasticity is determined as the percent recovery.

As used herein, the term “tenacity” refers to the measure of tensilestrength of a yarn as measured in grams per denier.

Examples 1-8

Bicomponent fibers with a polypropylene sheath and a SEBS elastomer coreat sheath/core ratios of 30/70 and 20/80 were made according to thefollowing description. The polypropylene sheath was a nominal 38 MFRhomopolymer (5D49) from The Dow Chemical Company. The elastomer core(Polymer 7) was a nominal 50 MFR, high vinyl (vinyl content=75 mol %),coupled SEBS copolymer (coupling efficiency=96%) with an 18% styrenecontent, a styrene MW of 6600 and a midblock molecular weight of 60,000.

The fibers were made using a conventional, commercial-type high speedspinning process using bicomponent technology and spinnerets from HillsInc.

Table 1 gives typical spinning performance and mechanical properties ofthe fibers. From Table 1, one can see that high speed spinning can beachieved (Examples 3 5, and 8) as well as reasonable fiber tensilestrength and elongation-to-break (Examples 1, 2, 4, 6, 7). Exceptionallyhigh spinning speeds were attainable. The sheath-core bicomponent fibers(Examples 3 and 5) were spun at 2700 mpm.

Examples 9-13

Bicomponent fibers with a polypropylene sheath and a SEBS elastomer coreat sheath/core ratios of 30/70 and 20/80 were made according to thefollowing description. The polypropylene sheath was a nominal 38 MFRhomopolymer (5D49) from The Dow Chemical Company. The elastomer core(Polymer 5) was a 31 MFR, high vinyl (vinyl content=76%), coupled SEBScopolymer (coupling efficiency=94%) with an 18% styrene content, astyrene MW of 6200 and a midblock molecular weight of 56,000.

The fibers were made via a conventional, commercial-type high speedspinning process using bicomponent technology and spinnerets from HillsInc.

Good tensile properties could be achieved with the 31 MFR elastomer(Examples 9, 11 and 12). The attainable spinning speed was in the rangeof 1500 to 1800 mpm.

Examples 14-25

Bicomponent fibers with a polypropylene sheath and a SEBS elastomer coreat sheath/core ratios of 30/70 and 20/80 were made according to thefollowing description. The polypropylene sheath was a nominal 38 MFRhomopolymer (5D49) from The Dow Chemical Company. The elastomer core(Polymer 6) was a nominal 20 MFR, high vinyl (vinyl content=76%),coupled SEBS copolymer (coupling efficiency=95%) with an 19% styrenecontent, a styrene MW of 6100 and a midblock molecular weight of 50,000.

The fibers were made via a conventional, commercial-type high speedspinning process using bicomponent technology and spinnerets from HillsInc.

The results of Table 3 demonstrate that a lower melt flow elastomer hasa detrimental effect on the spinning performance (maximum spinningspeed) but the tensile properties are still considered to be reasonablefor an elastic fiber. Table 3 also shows that as the polypropylenebecomes a greater portion of the fiber cross-section that spinningperformance improves and that even relatively low melt flow elastomerscan offer good spinning performance with the correct sheath/core ratio.In addition, the polypropylene improves the tensile strength of thefibers as its concentration increases but probably has a negative effecton the fiber elasticity.

Examples 26-36

Bicomponent fibers with a polypropylene sheath and a SEBS elastomer coreat sheath/core ratios of 30/70 and 20/80 were made according to thefollowing description. The polypropylene sheath was a nominal 38 MFRhomopolymer (5D49) from The Dow Chemical Company. The elastomer core wasa blend with polypropylene (5D49) and an elastomer (Polymer 7). Blend 1was a blend of 10 wt % Dow 5D49 polyproplene with 90 wt % Polymer 7.Blend 2 was a blend of 20 wt % Dow 5D49 polypropylene with 80 wt %Polymer 7.

The fibers were made via a conventional, commercial-type high speedspinning process using bicomponent technology and spinnerets from HillsInc. Table 4 demonstrates that elastomer blends with polypropylene madegood elastomeric cores for bicomponent elastic fibers. High spinningspeeds and good tensile and elastic properties were achieved.

A comparative monocomponent fiber (Example 36) is also shown in Table 4.The monocomponent fiber consisted only of the elastomer compound(Polymer 7) and no thermoplastic polymer sheath. Low spinning speedswere required and the fibers exhibited unacceptable stickiness duringthe spinning process. The resulting monocomponent fibers self-adheredand could not be separated.

Examples 37-39

Bicomponent fibers were also spun via a single air aspirator to simulatea spunbond process. Air pressure in the aspirator was used to affect themaximum spinning speed, i.e., the higher the pressure the higher thespinning speed. For all of the examples the polymer throughput per hole(0.35 g/hole/min) is the same.

Example 37 was a comparative monocomponent fiber of 5D49 polypropylenealone. The maximum air pressure reached 40 psi before fibers began tobreak. The fibers of this thermoplastic polymer had little or noelasticity.

Example 38 used a 5D49 polypropylene sheath and a 50 MFR elastic core(Polymer 7) at a 20/80 ratio to produce elastic spunbond fibers. Themaximum spinning speed was 20 psi before filaments began to break.Example 39 was a bicomponent fiber of polypropylene (5D49) and a 20 MFRelastomer (Polymer 6) at a sheath/core ratio of 40/60. The maximumspinning speed was 25 psi before fibers began to break. The bicomponentfibers of Examples 38 and 39 were elastic.

Example 40-45

Examples 40 through 44 demonstrate sheath/core bicomponent fibers usingDow ASPUN polyethylene as the thermoplastic polymer sheath (6811A) andPolymer 7 as the elastomeric core. These examples demonstrate thatpolyethylene can also be used as a sheath for bicomponent elasticfibers.

The fibers were made via a conventional, commercial-type high speedspinning process using bicomponent technology and spinnerets from HillsInc.

Example 46

A bicomponent elastic fiber was made with a relatively low melt flowrate, low vinyl elastomer (Polymer 8) according to the followingdescription. Polymer 8 was a nominal 9 MFR, 38% vinyl coupled SEBSelastomer. It has a styrene block molecular weight of 5000, a midblockmolecular weight of 47,000, and a coupling efficiency of 94%. Thenominal styrene content is 18 wt %. The sheath for this fiber is anominal 12 MFR homopolymer polypropylene.

Examples 47-55

Bicomponent filaments were made having a polypropylene sheath and a SEBSelastomer core at sheath/core ratios of 30/70 and 20/80. Thepolypropylene sheath was a nominal 38 MFR homopolymer (5D49) from TheDow Chemical Company. The elastomer core is a blend of 90 wt % highvinyl SEBS block copolymer (Polymer 1) and 10 wt % Regalrez 1126tackifier. Polymer 1 had a nominal 20% styrene content, a styrene MW of6,200 daltons and a midblock molecular weight of 50,000 daltons. Thevinyl content of the EB block was 77%. The blended elastomeric compoundhad a melt flow of 55 g/10 min. The filaments were made via aconventional high speed spinning process using bicomponent technologyand spinnerets from Hills Inc. Table 8 gives typical spinningperformance and mechanical properties of the filaments. The spinnerethole size was 0.35 mm with 72 holes. Table 8 shows that high speedspinning can be achieved (Examples 49, 50, 51, 53, 54 and 55) as well asreasonable fiber tensile strength and elongation to break. The fibers inthese examples exhibited fair to good elasticity.

Examples 56-62

Examples 56-62 were bicomponent sheath/core fibers made with apolypropylene sheath and a SEBS copolymer/tackifier blend as the coreaccording to the method of Examples 47-55. The SEBS copolymer (Polymer2) was a nominal 40% vinyl (1,2 butadiene addition), 22% styrene blockcopolymer. The styrene peak molecular weight was approximately 5300daltons and the midblock peak molecular weight was approximately 38,000daltons. The tackifier was Regalrez 1126. The melt flow of the Polymer2/tackifier blended elastomeric compound was 50 g/10 min with 10 wt %tackifier and 90 wt % Polymer 2. Compared to Examples 47-55, Examples56-62 were measurably stronger (tenacity) but had similar elongation tobreak (toughness) and elasticity. At a 10/90 sheath/core ratio thetensile strength decreased but the elasticity increased significantlybecause the rubber content was higher.

Example 63

Example 63 was a bicomponent sheath/core fiber with a polypropylenesheath and a VISTAMAXX® polypropylene (VM2125)/Polymer 1 blend as thecore according to the method. The blend was 25 wt % VISTAMAXXpropropylene and 75 wt % Polymer 1. The melt flow of Polymer 1 was_(—)24g/10 min. The melt flow of the blended elastomeric compound was_(—)32g/10 min. Example 63 in Table 10 demonstrates that the VISTAMAXX/blockcopolymer blend is melt spinnable and that reasonable fiber propertiesare attainable.

TABLE 1 Spinning Elongation Highest Denier per Sheath/Core SpeedTenacity at Break Elasticity Spinning Spinneret filament Example Ratio(mpm) (g/dn) (%) (%) Speed # of holes (dpf) 1 20/80  500 0.3 500 70 — 7215 2 20/80 1400 0.6 320 80 — 72   5.4 3 20/80 — — — — 2700 72 — 4 30/70 500 0.3 550 — — 72 15 5 30/70 — — — — 2700 72 — 6 20/80  500 0.2 560 —— 36 27 7 20/80 1500 0.3 280 — — 36   7.6 8 20/80 — — — — 3000 36 —

TABLE 2 Spinning Elongation Highest Sheath/Core Speed Tenacity at BreakElasticity Spinning Example Ratio (mpm) (g/dn) (%) (%) Speed 9 20/80 5000.3 470 — — 10 20/80 — — — — 1500 11 30/70 500 0.3 570 — — 12 30/701400  0.7 250 75 — 13 30/70 — — — — 1800

TABLE 3 Spinning Elongation Highest Denier per Sheath/Core SpeedTenacity at Break Elasticity Spinning filament Example Ratio (mpm)(g/dn) (%) (%) Speed (dpf) 14 20/80  500 0.3 500 — — 14.5 15 20/80 10000.5 310 — —  7.5 16 20/80 — — — — 1100 — 17 30/70  500 0.3 490 — — 14.518 30/70 1400 0.7 250 80 — 5  19 30/70 — — — — 1500 — 20 40/60  500 0.5660 — — 14.5 21 40/60 1400 0.8 320 — — 5  22 40/60 — — — — 1900 — 2350/50  500 0.5 660 — — 14.5 24 50/50 1400 0.9 330 50 — 5  25 50/50 — — —— 2500 —

TABLE 4 Highest Spinning Elongation Spinning Sheath/Core Speed Tenacityat Break Elasticity Speed Comments/denier per Example Core Ratio (mpm)(g/dn) (%) (%) (mpm) filament (dpf) 26 Blend 1 0/100 — — — — 800 Nosheath, very sticky 27 Blend 1 20/80  500 0.1 660 — —  21 dpf 28 Blend 120/80 1500 0.2 310 75 — 7.7 dpf 29 Blend 1 20/80 2000 0.4 200 — —   6dpf 30 Blend 1 20/80 — — — — 2700  — 31 Blend 2 0/100 — — — — 800 Nosheath, very sticky 32 Blend 2 20/80  500 0.2 530 — —  21 dpf 33 Blend 220/80 1500 0.3 200 70 — 7.7 dpf 34 Blend 2 20/80 2000 0.4 160 75 —   6dpf 35 Blend 2 20/80 — — — — 3000  — 36 Polymer 7 0/100 — — — — 800 Nosheath, very sticky

TABLE 5 Sheath/ Max Spinning Core Speed Elasticity Example Sheath CoreRatio (psi) (%) 37 5D49 — 100/0  40 20 38 5D49 Polymer 7 20/80 20 — 395D49 Polymer 6 40/60 25 75

TABLE 6 Denier Spinning per Elongation Highest Sheath/Core Speedfilament Tenacity at Break Elasticity Spinning Example Ratio (mpm)(g/9000 m) (g/dn) (%) (%) Speed 40 20/80 300 17.6 0.1 660 — — 41 20/80500 11.6 0.1 680 — — 42 20/80 — — — — —  500 43 30/70 500 11.6 0.1 58060 — 44 30/70 1000   5.2 0.2 360 50 — 45 30/70 — — — — — 1000

TABLE 7 Spinning Elongation Sheath/Core Speed Tenacity at BreakElasticity Example Ratio (mpm) (g/dn) (%) (%) 46 20/80 500 0.02 480 80

TABLE 8 Spinning Elongation Denier Per Sheath/Core Speed Tenacity atBreak Filament Example Ratio (mpm) (g/dn) (%) Elasticity (dpf) 47 30/701500 0.7 320 50 5.2 48 30/70 2000 0.8 250 50 3.8 49 30/70 2500 0.9 25050 3.3 50 30/70 3000 0.9 120 50 2.7 51 30/70 3500 1.2 180 50 2.3 5220/80 1500 0.6 260 60 5.2 53 20/80 2500 0.8 170 60 3.3 54 20/80 3000 1.0160 40 2.5 55 20/80 3500 0.9 140 40 2.4

TABLE 9 Sheath/ Spinning Elongation Core Speed Tenacity at Break Exampleratio (mpm) (g/dn) (%) elasticity dpf 56 30/70 1500 1.1 300 40 5.2 5730/70 2500 2.2 200 40 3.1 58 30/70 3000 2.1 170 40 2 59 20/80 1500 1.1330 70 5.3 60 20/80 2500 1.7 230 60 3 61 20/80 3000 1.6 180 60 2.6 6210/90 1500 0.9 390 90 4.3

TABLE 10 Sheath/ Spinning Elongation Core Speed Tenacity at BreakExample Ratio (mpm) (g/dn) (%) dpf Elasticity 63 20/80 1500 0.6 230 5.170

1. A bicomponent fiber comprising a thermoplastic polymer and anelastomeric compound wherein the elastomeric compound consistsessentially of a selectively hydrogenated block copolymer having an Sblock and an E or E₁ block and having the general formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)X or mixtures thereof, wherein:a. prior to hydrogenation the S block is a polystyrene block; b. priorto hydrogenation the E block is a polydiene block, selected from thegroup consisting of polybutadiene, polyisoprene and mixtures thereof,having a molecular weight from 40,000 to 70,000; c. prior tohydrogenation the E₁ block is a polydiene block, selected from the groupconsisting of polybutadiene, polyisoprene, and mixtures thereof, havinga molecular weight from 20,000 to 35,000; d. n has a value of 2 to 6 andX is the residue of a coupling agent; e. the styrene content of theblock copolymer is from 13 to 25 weight percent; f. the vinyl content ofthe polydiene block prior to hydrogenation is from 70 to 85 mol percent;g. the block copolymer includes less than 15 weight percent of unitshaving the general formula:S-E or S-E₁ wherein S, E and E₁ are as already defined; h. subsequent tohydrogenation about 0 to 10% of the styrene double bonds have beenhydrogenated and at least 80% of the conjugated diene double bonds havebeen hydrogenated; i. the molecular weight of each of the S blocks isfrom 5,000 to 7,000 and a tackifying resin, wherein the melt flow rateof the block copolymer is at least 15 g/10 min at 230° C. and 2.16 kgweight according to ASTM D1238.
 2. The bicomponent fiber of claim 1wherein the tackifying resin is from 5 to 30 wt % basis the elastomericcompound mass.
 3. The bicomponent fiber of claim 1 wherein thepolystyrene content of the block copolymer is from 15 to 24 weightpercent.
 4. The bicomponent fiber of claim 1 wherein the polydieneblocks E and E₁ have a vinyl content from 73 to 83 mol percent.
 5. Thebicomponent fiber of claim 1 wherein the molecular weight of thepolystyrene block S is from 5,800 to 6,600.
 6. The bicomponent fiber ofclaim 1 wherein the E block is polybutadiene having a molecular weightfrom 45,000 to 60,000, or the E₁ block is two or more coupledpolybutadiene blocks, each of the polybutadiene blocks, prior to beingcoupled, has a molecular weight from 22,500 to 30,000.
 7. Thebicomponent fiber of claim 6 wherein the coupling agent is selected fromthe group consisting of tetramethoxy silane, tetraethoxy silane,tetrabutoxy silane, tetrakis(2-ethylhexyloxy) silane, methyl trimethoxysilane, methyl triethoxy silane, isobutyl trimethoxy silane, phenyltrimethoxy silane, silicon tetrachloride, methyl-trichlorosilane anddimethyl-dichlorosilane.
 8. The bicomponent fiber of claim 1 wherein thestructure of the selectively hydrogenated block copolymer is (S-E₁)_(n)Xand the block copolymer contains less than 10% of an uncoupled S-E₁species.
 9. The bicomponent fiber of claim 1 wherein the melt flow rateof the block copolymer is at least 40 g/10 min at 230° C. and 2.16 kgweight according to ASTM D1238.
 10. The bicomponent fiber of claim 1wherein the thermoplastic polymer is selected from the group consistingof polypropylene, polyethylene, polyamides, poly(ethyleneterephthalate), poly(butylene terephthalate), and poly(trimethyleneterephthalate).
 11. The bicomponent fiber of claim 10 wherein thethermoplastic polymer is polypropylene having a melt flow of at least 20g/10 min at 230° C. and 2.16 kg according to ASTM D1238.
 12. Thebicomponent fiber of claim 10 wherein the thermoplastic polymer islinear low density polyethylene having a melt flow of at least 25 g/10min at 190° C. and 2.16 kg according to ASTM D1238.
 13. The bicomponentfiber of claim 1 having a sheath-core morphology wherein the coreconsists of the elastomeric compound and the sheath consists primarilyof the thermoplastic polymer.
 14. The bicomponent fiber of claim 13wherein the volume ratio of thermoplastic polymer sheath to elastomericcompound core is from 1/99 to 50/50.
 15. The bicomponent fiber of claim1 having an islands-in-the-sea morphology wherein the islands consistprimarily of the elastomeric compound and the sea consists primarily ofthe thermoplastic polymer.
 16. The bicomponent fiber of claim 15 whereinthe volume ratio of thermoplastic polymer sea to elastomeric compoundislands is from 1/99 to 50/50.
 17. The bicomponent fiber of claim 1having a denier from 0.5 to
 20. 18. An article comprising thebicomponent fiber of claim 1 which is an elastic mono-filament, a wovenfabric, a spunbond non-woven fabric, a melt-blown non-woven fabric orfilter, a staple fiber, a yarn or a bonded, carded web.
 19. Abicomponent fiber comprising a thermoplastic polymer and an elastomericcompound wherein the elastomeric compound consists essentially of aselectively hydrogenated block copolymer having an S block and an E orE₁ block and having the general formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)X or mixtures thereof, wherein:a. prior to hydrogenation the S block is a polystyrene block; b. priorto hydrogenation the E block is a polydiene block, selected from thegroup consisting of polybutadiene, polyisoprene and mixtures thereof,having a molecular weight from 40,000 to 70,000; c. prior tohydrogenation the E₁ block is a polydiene block, selected from the groupconsisting of polybutadiene, polyisoprene, and mixtures thereof, havinga molecular weight from 20,000 to 35,000; d. n has a value of 2 to 6 andX is the residue of a coupling agent; e. the styrene content of theblock copolymer is from 13 to 25 weight percent; f. the vinyl content ofthe polydiene block prior to hydrogenation is from 35 to 50 mol percent;g. the block copolymer includes less than 15 weight percent of unitshaving the general formula:S-E or S-E₁ wherein S, E and E₁ are as already defined; h. subsequent tohydrogenation about 0 to 10% of the styrene double bonds have beenhydrogenated and at least 80% of the conjugated diene double bonds havebeen hydrogenated; i. the molecular weight of each of the S blocks isfrom 5,000 to 7,000 and any one of a tackifying resin, an alpha-olefincopolymer, an alpha-olefin terpolymer, a wax or mixtures thereof,wherein the melt index of the block copolymer is at least 15 grams/10minutes at 230° C. and 2.16 kg weight according to ASTM D1238.
 20. Thebicomponent fiber of claim 19 wherein the melt index of the elastomericcompound is at least 40 grams/10 minutes according to ASTM D1238 at 230°C. and 2.16 kg weight.
 21. The bicomponent fiber of claim 19 wherein thealpha-olefin copolymer is selected from the group consisting ofethylene/alpha-olefin copolymers and propylene/alpha-olefin copolymers.22. The bicomponent fiber of claim 19 wherein the alpha-olefinterpolymer is selected from the group consisting ofethylene/propylene/alpha-olefin terpolymers,ethylene/styrene/alpha-olefin terpolymers andpropylene/styrene/alpha-olefin terpolymers.
 23. The bicomponent fiber ofclaim 19 wherein the tackifying resin, alpha-olefin copolymer oralpha-olefin terpolymer is from 5 to 30 wt % basis the elastomericcompound mass.
 24. The bicomponent fiber of claim 19 having asheath-core morphology wherein the core consists of the elastomericcompound and the sheath consists primarily of the thermoplastic polymer.25. The bicomponent fiber of claim 24 wherein the volume ratio ofthermoplastic polymer sheath to elastomeric compound core is from 1/99to 50/50.
 26. The bicomponent fiber of claim 19 having anislands-in-the-sea morphology wherein the islands consist primarily ofthe elastomeric compound and the sea consists primarily of thethermoplastic polymer.
 27. The bicomponent fiber of claim 26 wherein thevolume ratio of thermoplastic polymer sea to elastomeric compoundislands is from 1/99 to 50/50.
 28. The bicomponent fiber of claim 19having a denier from 0.5 to
 20. 29. An article comprising thebicomponent fiber of claim 19 which is an elastic mono-filament, a wovenfabric, a spunbond non-woven fabric, a melt-blown non-woven fabric orfilter, a staple fiber, a yarn or a bonded, carded web.
 30. Abicomponent fiber comprising a thermoplastic polymer and an elastomericcompound wherein the elastomeric compound consists essentially of aselectively hydrogenated block copolymer having an S block and an E orE₁ block and having the general formula:S-E-S,(S-E₁)_(n),(S-E₁)_(n)S,(S-E₁)_(n)X or mixtures thereof, wherein:j. prior to hydrogenation the S block is a polystyrene block; k. priorto hydrogenation the E block is a polydiene block, selected from thegroup consisting of polybutadiene, polyisoprene and mixtures thereof,having a molecular weight from 40,000 to 70,000; l. prior tohydrogenation the E₁ block is a polydiene block, selected from the groupconsisting of polybutadiene, polyisoprene, and mixtures thereof, havinga molecular weight from 20,000 to 35,000; m. n has a value of 2 to 6 andX is the residue of a coupling agent; n. the styrene content of theblock copolymer is from 13 to 25 weight percent; o. the vinyl content ofthe polydiene block prior to hydrogenation is from 70 to 85 mol percent;p. the block copolymer includes less than 15 weight percent of unitshaving the general formula:S-E or S-E₁ wherein S, E and E₁ are as already defined; q. subsequent tohydrogenation about 0 to 10% of the styrene double bonds have beenhydrogenated and at least 80% of the conjugated diene double bonds havebeen hydrogenated; r. the molecular weight of each of the S blocks isfrom 5,000 to 7,000 and any one of an alpha-olefin copolymer, analpha-olefin terpolymer, a wax or mixtures thereof wherein the meltindex of the block copolymer is at least 15 grams/10 minutes at 230° C.and 2.16 kg weight according to ASTM D1238.
 31. The bicomponent fiber ofclaim 30 wherein the alpha-olefin copolymer is selected from the groupconsisting of ethylene/alpha-olefin copolymers andpropylene/alpha-olefin copolymers.
 32. The bicomponent fiber of claim 30wherein the alpha-olefin terpolymer is selected from the groupconsisting of ethylene/propylene/alpha-olefin terpolymers,ethylene/styrene/alpha-olefin terpolymers andpropylene/styrene/alpha-olefin terpolymers.
 33. The bicomponent fiber ofclaim 30 wherein the alpha-olefin copolymer or alpha-olefin terpolymeris from 5 to 49 wt % basis the elastomeric compound mass.
 34. Thebicomponent fiber of claim 30 having a sheath-core morphology whereinthe core consists of the elastomeric compound and the sheath consistsprimarily of the thermoplastic polymer.
 35. The bicomponent fiber ofclaim 30 wherein the volume ratio of thermoplastic polymer sheath toelastomeric compound core is from 1/99 to 50/50.
 36. The bicomponentfiber of claim 30 having an islands-in-the-sea morphology wherein theislands consist primarily of the elastomeric compound and the seaconsists primarily of the thermoplastic polymer.
 37. The bicomponentfiber of claim 36 wherein the volume ratio of thermoplastic polymer seato elastomeric compound islands is from 1/99 to 50/50.
 38. Thebicomponent fiber of claim 30 having a denier from 0.5 to
 20. 39. Anarticle comprising the bicomponent fiber of claim 30 which is an elasticmono-filament, a woven fabric, a spunbond non-woven fabric, a melt-blownnon-woven fabric or filter, a staple fiber, a yarn or a bonded, cardedweb.